Pressurized Storage Tanks have internal bladders made of polypropylene and are available from one gallon to 86 gallons. The internal bladder takes up some of the water capacity space. These types of tanks creates its own pressure as the tank fills up which is then released when the water is needed. Pressurized ro tanks are very economical.

Atmospheric tanks are usually much larger in size and can go as high as 25,000 gallons. Atmospheric Storage Tanks do not have or create any pressure and require a delivery pump of some sort in order to re-pressurize the water. These are perfect for people/businesses that need a whole building to have reverse osmosis water.